8 Photoelectric Effect Albert EinsteinProposed that light can be described as quanta of energy that behave as if they were particlesPhotons = light energyMetals eject electrons when specific wavelengths of light shines on themElectrons being ejectedLight energymetal

10 Atomic Spectra Electrons absorb energy and get “excited”When they are excited, they jump up to a new energy level (farther away from nucleus)The electron then loses that energy and falls back down to ground stateThe energy emitted produces the various colors of light that you see

11 Quantum MechanicsIf light behaves as waves and particles, can particles behave as waves?Question proposed by De Broglie (French graduate student)All matter exhibits wavelike motionsParticles gain or lose energy in packages called quantaHeisenberg uncertainty principleIt is impossible to know exactly both the velocity and position of a particle at the same time